Silvia Mangia1, Timo Liimatainen1, Michael Garwood1, Shalom Michaeli1
1Radiology, University of Minnesota,
Minneapolis, MN, USA
In the present work we investigate the frequency offset dependency of the rotating frame longitudinal, R1ρ, and transverse, R2ρ, relaxation rate constants during continuous-wave spin-lock irradiation and during hyperbolic secant adiabatic full passage pulses. We demonstrate, both theoretically and experimentally, that R1ρ and R2ρ induced by dipolar interactions and anisochronous exchange during hyperbolic secant pulses are minimally dependent on the frequency offsetwithin the bandwidth of the pulse, as opposite to continuous-wave irradiation. This is a unique advantage for MRS applications in vivo, because it allows "one shot" data acquisition over a wide range of chemical shift.